The U.S. Supreme Court has changed course after nearly 50 years by deciding that the touchstone of Fourth Amendment jurisprudence is trespass to a property interest, not reasonable expectation of privacy.

Police engaged in a “search” within the meaning of the Fourth Amendment when they used a drug-sniffing dog on a homeowner’s porch to investigate the contents of the home, the U.S. Supreme Court has ruled 5-4.